dns: Add support for MX queries

Due to an oversight, the internal DNS server supports MX record updates,
but not MX record queries. Add support for MX queries and tests.

This should fix bug #9485

Signed-off-by: Kai Blin <kai@samba.org>
Reviewed-By: Amitay Isaacs <amitay@gmail.com>

2 files changed, 51 insertions, 0 deletions

diff --git a/python/samba/tests/dns.py b/python/samba/tests/dns.py
index 49d699edb7..a29025d324 100644
--- a/python/samba/tests/dns.py
+++ b/python/samba/tests/dns.py
@@ -510,6 +510,49 @@ class TestDNSUpdates(DNSTest):
         response = self.dns_transaction_udp(p)
         self.assert_dns_rcode_equals(response, dns.DNS_RCODE_NXDOMAIN)
 
+    def test_update_add_mx_record(self):
+        "test adding MX records works"
+        p = self.make_name_packet(dns.DNS_OPCODE_UPDATE)
+        updates = []
+
+        name = self.get_dns_domain()
+
+        u = self.make_name_question(name, dns.DNS_QTYPE_SOA, dns.DNS_QCLASS_IN)
+        updates.append(u)
+        self.finish_name_packet(p, updates)
+
+        updates = []
+        r = dns.res_rec()
+        r.name = "%s" % self.get_dns_domain()
+        r.rr_type = dns.DNS_QTYPE_MX
+        r.rr_class = dns.DNS_QCLASS_IN
+        r.ttl = 900
+        r.length = 0xffff
+        rdata = dns.mx_record()
+        rdata.preference = 10
+        rdata.exchange = 'mail.%s' % self.get_dns_domain()
+        r.rdata = rdata
+        updates.append(r)
+        p.nscount = len(updates)
+        p.nsrecs = updates
+
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+
+        p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
+        questions = []
+
+        name = "%s" % self.get_dns_domain()
+        q = self.make_name_question(name, dns.DNS_QTYPE_MX, dns.DNS_QCLASS_IN)
+        questions.append(q)
+
+        self.finish_name_packet(p, questions)
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+        self.assertEqual(response.ancount, 1)
+        self.assertEqual(response.answers[0].rdata.preference, 10)
+        self.assertEqual(response.answers[0].rdata.exchange, 'mail.%s' % self.get_dns_domain())
+
 
 class TestComplexQueries(DNSTest):
 
diff --git a/source4/dns_server/dns_query.c b/source4/dns_server/dns_query.c
index 35921100e1..4ad14b9a55 100644
--- a/source4/dns_server/dns_query.c
+++ b/source4/dns_server/dns_query.c
@@ -92,6 +92,14 @@ static WERROR create_response_rr(const struct dns_name_question *question,
 	case DNS_QTYPE_PTR:
 		ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
 		break;
+	case DNS_QTYPE_MX:
+		ans[ai].rdata.mx_record.preference = rec->data.mx.wPriority;
+		ans[ai].rdata.mx_record.exchange = talloc_strdup(
+			ans, rec->data.mx.nameTarget);
+		if (ans[ai].rdata.mx_record.exchange == NULL) {
+			return WERR_NOMEM;
+		}
+		break;
 	case DNS_QTYPE_TXT:
 		tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
 		W_ERROR_HAVE_NO_MEMORY(tmp);